The present invention relates to an apparatus and method for performing tests on a sample of body fluid to be analyzed, and more particularly to a spectrophotometer having multiple readheads and a method for analyzing a reagent strip using multiple readheads.
It is useful for various medical diagnostic purposes to utilize a spectrophotometer to analyze samples of body fluid, for example, to determine the color of a person's urine. A conventional spectrophotometer determines the color of a urine sample disposed on a white, non-reactive pad by illuminating the pad and taking a number of reflectance readings from the pad, each having a magnitude relating to a different wavelength of visible light. The color of the urine on the pad may then be determined based upon the relative magnitudes of red, green and blue reflectance signals.
Conventional spectrophotometers may be used to perform a number of different urinalysis tests utilizing a reagent strip on which a number of different reagent pads are disposed. Each reagent pad is provided with a different reagent which causes a color change in response to the presence of a certain type of constituent in urine, such as leukocytes (white blood cells) or red blood cells. Such a reagent strip may have ten different types of reagent pads.
U.S. Pat. No. 4,689,202 to Khoja, et al. discloses a reagent test strip reading instrument having a pair of readheads adapted to optically inspect reagent strips and a conveyor system that transports reagent strips to the readheads. In the Khoja, et al. system, the readheads are adapted to read different, predetermined portions of a reagent strip. In particular, as described in column 11, lines 15-21 of the Khoja, patent, the fiber optics for reading the seven test areas on a reagent strip having a shorter incubation time are mounted on readhead 124 in position for alignment with such areas, and the fiber optics for reading the reagent test areas having the relatively longer incubation time are mounted on the readhead 125 in position for alignment with those areas.